DV164136 Microchip Technology, DV164136 Datasheet - Page 36

• Manufacturer Part Number: DV164136
• Description: DEVELOPMENT KIT FOR PIC18
• Manufacturer: Microchip Technology
• Series: PIC®r
• Type: MCUr

Specifications of DV164136

• Contents: Board, Cables, CDs, PICkit™ 3 Programmer, Power Supply
• Processor To Be Evaluated: PIC18F8722, PIC18F87J11
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3.3 V, 5 V
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18F8xxx
• Kit Contents: PIC18 Exp Brd PICkit 3 Cable CD PSU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PIC18F8722, PIC18F87J11
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC18F87J11 FAMILY
2.3.1
The
(OSCCON<1:0>), select the clock source. The avail-
able clock sources are the primary clock defined by the
FOSC2:FOSC0 Configuration bits, the secondary
clock (Timer1 oscillator) and the internal oscillator. The
clock source changes after one or more of the bits are
written to, following a brief clock transition interval.
The OSTS (OSCCON<3>) and T1RUN (T1CON<6>)
bits indicate which clock source is currently providing
the device clock. The OSTS bit indicates that the
Oscillator Start-up Timer (OST) has timed out and the
primary clock is providing the device clock in primary
clock modes. The T1RUN bit indicates when the
Timer1 oscillator is providing the device clock in sec-
ondary clock modes. In power-managed modes, only
one of these bits will be set at any time. If neither of
these bits is set, the INTRC is providing the clock, or
the internal oscillator has just started and is not yet
stable.
The IDLEN bit determines if the device goes into Sleep
mode or one of the Idle modes when the SLEEP
instruction is executed.
The use of the flag and control bits in the OSCCON
register is discussed in more detail in Section 3.0
“Power-Managed Modes”.
DS39778D-page 36
Note 1: The Timer1 oscillator must be enabled to
System
2: It is recommended that the Timer1
CLOCK SOURCE SELECTION
select the secondary clock source. The
Timer1 oscillator is enabled by setting the
T1OSCEN bit in the Timer1 Control regis-
ter (T1CON<3>). If the Timer1 oscillator is
not enabled, then any attempt to select a
secondary clock source when executing a
SLEEP instruction will be ignored.
oscillator be operating and stable before
executing the SLEEP instruction or a very
long delay may occur while the Timer1
oscillator starts.
Clock
Select
bits,
SCS1:SCS0
oscillator, will have two bit setting options for the possible
2.3.1.1
Since the SCS bits are cleared on all forms of Reset,
this means the primary oscillator defined by the
FOSC2:FOSC0 Configuration bits is used as the
primary clock source on device Resets. This could
either be the internal oscillator block by itself, or one of
the other primary clock source (HS, EC, HSPLL,
ECPLL1/2 or INTPLL1/2).
In those cases when the internal oscillator block, with-
out PLL, is the default clock on Reset, the Fast RC
oscillator (INTOSC) will be used as the device clock
source. It will initially start at 4 MHz; the postscaler
selection that corresponds to the Reset value of the
IRCF2:IRCF0 bits (‘110’).
Regardless of which primary oscillator is selected,
INTRC will always be enabled on device power-up. It
serves as the clock source until the device has loaded
its configuration values from memory. It is at this point
that the FOSC Configuration bits are read and the
oscillator selection of the operational mode is made.
Note that either the primary clock source, or the internal
values of the SCS1:SCS0 bits at any given time.
2.3.2
PIC18F87J11 family devices contain circuitry to
prevent clock “glitches” when switching between clock
sources. A short pause in the device clock occurs dur-
ing the clock switch. The length of this pause is the sum
of two cycles of the old clock source and three to four
cycles of the new clock source. This formula assumes
that the new clock source is stable.
Clock transitions are discussed in greater detail in
Section 3.1.2 “Entering Power-Managed Modes”.
OSCILLATOR TRANSITIONS
System Clock Selection and Device
Resets
© 2009 Microchip Technology Inc.